Reciprocatory hammer tool



Patented June 15, 1926. I,

UNITED sTATssrAi-ENT orifice.

' FRANCIS JIMER.SON, 0F ATHENS, PENNSYLVANIA. ASSIGNORTO INGERSOLL-R-AND COMPANY, OF JERSEY CITY, IFF-W JERSEY, ACORPORATION OF NEW JERSEY.

nnciraocaromr HAMMER Toor..

Application med October 29, 1924. Serial No. 746,464. i

This invention relates to fluid actuated hammer tools, and more particularly to a valve motion for controlling the movements of the piston withinvt-he cylinder.

In hand held fluid actuated percussive tools of the free exhaust type,that is,those which are provided with a central exhaust controlled by the hammer piston, compression is desirable on the back stroke ot: the

piston since the' force of the returning piston' is gradually absorbed so that the operator receives less shock. On the forward stroke, however, it is desirable Vto relieve the com pression so that the hammer may d eliverits full force to the bit. It is not d'itlicult to provide an arrangement for relieving the compressionat both ends of the cylinder as this has heretofore been the practice. This invention, however, .provides a means for relieving` the compression at the front end of the cylinder so as not to retard tlie'ha'mmer piston while full compression is maintained on the rearward stroke to. relieve the operatorof the shock and to make an easy holding tool. l.

i One objectof this invention isvto provide for the escape otcoinpression on the forward end of the cylinder through the 1nterior of the valve'.

Other objects of the invention willbein part, obvious and in part pointed out in .the following description taken in conjunction with the accompanying drawings2 1n which Figure 1 is a longitudinal sectional view T:5 of a hammer tool constructed in accordance with the practice of the invention and shows the valve in its operatingr position at the liegrinning of the forward stroke of .the hammer piston.

el 4Figure ltis a longitudinal section of the hammer tool showing the piston beginning its return stroke, the valve being in its corresponding position.

Referring to the drawings. the hammer 15 tool comprises a cylinder A having a pair of piston controlled, free exhaust ports B and C" leading to atmosphere through the opening D in the cylinder wall. A tool E, such as a chiselorother suitable bit, is

.o adapted to be inserted so as to project -into the front end of the cylinder A in the path of the.reciprocating iston F. The movements of the iston, g are controlled ,by a oylindric'alvvav ve G which is adapted to reciprocate in a valve chamber H set in the back of the cylinder A. y

The valve chamber H is closed at 'its rear end by the back head J which is attached to the cylinder 'A by suitable bolts K. Thel handle part of'which is shownat L is also heldonto the back head J by the bolts K and a cross piece Of The valve chamber H is providedwith a pair Ott supply ports P and Q extending from a supply passage R which is associated with a suitable source (not shown) of coni-y l pressed air., The ports AP and Q lead to the vfront and rear ends of the valve chamber Hl in front and behind the valve Gr4 vTh'econipressed air. ory other suitablenio'tive duid, is admitted intothe cylinder `vA from the valve chamber H through inlet ports S and T which lead to the rear and front ends of the cylinder A. respectively.' T/he port T .entends through the back head Jut-o a longitudinal passage U in the cyliiider wall tothe front end of the cylinder. The valve chamber H is also provided with a port V leading to atmosphere through the cylinder wall and is arranged to cooperate with a passage leadmg'fronx the port T associated with the iront end 0i the. cylinder" A. This passage is provided in the valve G and inpassage lT and the port T into the interior' of the valve lV and tlicncethrough the hole.

X and the annular groove Y and the port V to atmosphere.. f

In order to tlrrow the valve G, there are. provided end 'pressure areas 71 andV which are constantl)- exposed to live air pressure from the supply ports P and Q respectively.

The pressure areas I; and c oppose eachother and cause the valve to moveJ in one direction -or the -other when vthe piston F passes one of the, exhaust ports B` or C to lower the pressure of the'motive tiuid on one of these faces. For instance, when the valve G is in the position shown in Figure l and the piston -F has advanced far enough to uncover the exhaust port C, the pressure on the area b dropsfbecause "of the exhaust of air behind the piston'through the exhaust port. Under these conditions the full line pressure on the area c is sullici'ent to cause `follows: assuming that the .piston F//and the valve G are in the position -shown in Figure l, inolive Huid is supplied from the supply port-P through the inlet port S into the cylihder A behind the piston F forcing it forivard to strike against the tool E. As the piston F advances the air-.compressed in front-of-the'piston'escapes through the e'xhaust port B until the latter is coveredby the piston whereupon the air--is compressed through the passage Uand the port T and is exhausted to atmosphere through the bore ll", the.,vv radial holes X and the ringport Y of thevalvc G and the port V' to v'atmosphere; Tllere can therefore be substantially no compression in the forward end of the cylinder A to retard the movement of the piston Fjn its movement toward the `tool E. v`Wben-the rear edge ofthe piston F uncovers 'the exhaust port C, the pressure on the forward 'faceof the valve G is immediatellx7 reduced so as to be less in amount thanltheV pressure on the. opposite. end area c whereupon the valve G acting-under the unbalanced pressure moves forward to the position shown in Figure 2. This motion causes the 'portlv`l to be blanked by the outer surface of; `tbe Valve G and simultaneously closes the ports S, at the same time opening the inlet port T leading to the forward end of the cylinder A and motive fluid passes thereto lirom the supply port T. .T he piston F then fis returned by the live motive Huid advancinliy against the compression on its backward face. The exhaust port C is first closed which traps the air in the rearward end of the cylinder A and as theiston F moves backwardly in-the cylinder, t is air is compressed absorbing the energy of the returning piston and relieving the shock. 'As the piston F uncovers the exhaust'port B, the

i. pressure at the inlet port T drops, causing a correspondingdecrease in pressure on the rear face of the` valve whereupon the combined compression in the rearwardend of the cylinder A and the live air pressure against the end area b causes the valve G to move in the direction the piston F is moving to open the inlet port S. The piston F is'y then forced forward under the pressure The construction of 'the valve G, as above described, provides a .very simply manufactured arrangement which is very reliable in operation. It will also be 'noted that the position-of the valve chamber set into the rear end of the cylinder A provides an arrangement which can be easily assembled.

rea-rends of said cylinder and the opposite i ends of said valve chamber, supply passages leading to the said opposite ends of sa-id valve chamber from a. source of pressure duid, a port ventingto atmosphere'from said'valve chamber and located, centrally thereof la cylindrical valve located and adapted to reciprocate within said valve chamber, said valve being provided with end pressure areas constantly 1n ,communication with the supply passage to actuate the yalve,

and a passage in said valve body constantly in communication'with the inlet port to lthe front'` end of the cylinder and leading -into a peripheral groove' encircling the said valve body which is adapted tocommunicate with the said atmospheric vent inthe` valve chamber while the piston is traveling forwardly. l l

2. A fluid actuated hammertoolcomprisj ing 'a cylinder having af piston\eontrolled exhanst port, a hamlnerpiston within the.

cylinder, .a valve chamber set in the rear end of said cylinder, supply passages leading :froml a source of pressure fluid to opposite ends of said valve chamber;v inlet ports leading from the said valve chamber to, the front and rearends of thesaid: cylinder,-an atmospheric ventmidway between .the ends of the valve chamber a pressure fluid thrown valve inthe valve chamber for ,regulating the admission of motive fluid to' i the cylinder, and adapted to reciprocate in said valve chamber, a peripheral groove around said valve and a port in said valve constantly in communication with said ront endojthe cylinder to atmosphere.

. are in communication, thereby venting the In testimony whereof I have signed this'- specification.

FRANCIS 1a.. Jameson.. 

